1. Field of the Invention
The present invention relates to an image recognition system using the light-section method, in which linear light is projected onto an object to be measured, to form a linear light image on the object and this image is picked up to obtain three-dimensional configuration data on the object.
2. Description of the Related Art
In an image recognition system using the light-section method, an image of linear light which has been projected onto the object by a light projector means must be accurately picked up in order to ensure improved accuracy in the recognition of the configuration of the object. In other words, picking up of a linear light image must be done so as to enable a thinning process by which the linear light is represented by a line having an infinitely small width which is normally the width of one pixel in ordinary image processing.
The image pickup means for picking up an image of an object onto which linear light is projected has a diaphragm mechanism for adjusting the amount of admitted light. If a diaphragm aperture is inappropriate, the above thinning process to express a linear light as a line of one pixel width becomes difficult. More specifically, when picking up an image of the same linear light projected onto an object, if the aperture is small, the picked-up light image becomes thick, so that variations are created in the thinning process, causing zigzag portions on the image of the linear light after thinning. On the other hand, if the aperture is large, the picked-up light image becomes thin, resulting in discontinuous portions in the image of the linear light after thinning. In both cases, the linear light cannot be represented by a line of one pixel width, which causes a defect in the image recognition of the light as a line.
To solve this problem, diaphragm aperture settings are predetermined on the basis of object conditions and illumination intensity.
Such a system, however, has little flexibility and versatility because of preliminarily fixed aperture settings according to object conditions and illumination intensity. In addition, light projection by use of a light projector means needs to be carried out at all times in order to obtain constant illumination intensity, which shortens the service life of the light projector means.
The present invention is directed to overcoming these problems and one of the objects of the invention is therefore to provide an image recognition system using the light-section method, which provides versatility and does not lead to a reduction in the service life of the light projector means.